Environmental Management (2014) 53:1146–1157 DOI 10.1007/s00267-014-0270-6

Changing Ecosystem Service Values Following Technological Change Jordi Honey-Rose´s • Daniel W. Schneider Nicholas Brozovic´

•

Received: 4 February 2013 / Accepted: 24 March 2014 / Published online: 22 April 2014  Springer Science+Business Media New York 2014

Abstract Research on ecosystem services has focused mostly on natural areas or remote places, with less attention given to urban ecosystem services and their relationship with technological change. However, recent work by urban ecologists and urban designers has more closely examined and appreciated the opportunities associated with integrating natural and built infrastructures. Nevertheless, a perception remains in the literature on ecosystem services that technology may easily and irreversibly substitute for services previously obtained from ecosystems, especially when the superiority of the engineered system motivated replacement in the first place. We emphasize that the expected tradeoff between natural and manufactured capital is false. Rather, as argued in other contexts, the adoption of new technologies is complementary to ecosystem management. The complementarity of ecosystem services and technology is illustrated with a case study in Barcelona, Spain where the installation of sophisticated water treatment technology increased the value of the

J. Honey-Rose´s (&) School of Community and Regional Planning, University of British Columbia, 1933 West Mall, Vancouver, BC V6T 1Z2, Canada e-mail: [email protected] D. W. Schneider Department of Urban and Regional Planning, University of Illinois, Urbana-Champaign, 111 Temple Buell Hall, 611 Taft Drive, Champaign, IL 61820, USA e-mail: [email protected] N. Brozovic´ Department of Agricultural and Consumer Economics, University of Illinois, Urbana-Champaign, 1301 W. Gregory Dr., Urbana, IL 61801, USA e-mail: [email protected]

123

ecosystem services found there. Interestingly, the complementarity between natural and built infrastructures may remain even for the very ecosystems that are affected by the technological change. This finding suggests that we can expect the value of ecosystem services to co-evolve with new technologies. Technological innovation can generate new opportunities to harness value from ecosystems, and the engineered structures found in cities may generate more reliance on ecosystem processes, not less. Keywords Ecosystem services
Green infrastructure
Desalination
Urban ecosystems
Natural capital
Substitution
Technology
Water treatment
Urban planning

Introduction Research on ecosystem services has focused mostly on natural areas or remote places that harbor biological diversity (Naidoo and Ricketts 2006; Armsworth et al. 2007; Fisher et al. 2011). Less attention has been given to ecosystem services in human-dominated landscapes (but see Goldstein 2007; Kareiva et al. 2007; Eigenbrod et al. 2009; Bai et al. 2011). The focus on natural settings is driven by the assumption that ecosystem services are more likely to emerge from places untouched by human settlement. Urban environments or impaired ecosystems, by contrast, are rarely associated with ecosystem services, but rather with engineered structures, artificial materials, and technology. The notion of ecosystem services was first developed by conservation biologists in collaboration with economists to find new arguments for ecosystem protection (Ehrlich and Mooney 1983; Daily 1997). This origin has left an imprint

Environmental Management (2014) 53:1146–1157

on the field, as researchers are far more likely to examine ecosystem services in biologically rich countries, often in the developing world, rather than in industrialized nations (Norgaard 2010). Ideas about ecosystem services were well received by many in the developing world because they unified conservation and development goals (Sachs and Reid 2006). It gave the land-owners of biologically rich areas a new reason for stewardship, and the programs that paid for ecosystem services provided financial incentives for conservation (Wunder 2007). Only more recently, scholars have turned their attention to ecosystem services emerging from cities and urban areas (Go´mez-Baggethun and Barton 2013; McDonald et al. 2013). Interest in urban ecosystem services has grown considerably in the last decade, with the number of articles published on the subject increasing exponentially (Hubacek and Kronberg 2013). Studying ecosystem services in an urban context invites us to re-examine the relationship between ecosystem services and the built environment. This paper focuses on ecosystem services that may emerge from non-pristine environments and examines the relationship between technological change and the value of ecosystem services. This examination may facilitate the integration of ecosystem service management in urban contexts. Planners and urban designers have shown interest in integrating the natural and built environment (Pickett et al. 2013) and applying our knowledge of natural processes to inform urban design (Ellin 2013; Shannon 2013). While the integration of urban and natural infrastructure has been at the center of discussions on green design and green infrastructure, the potential for this integration remains largely unnoticed in the field of ecosystem services. We seek to advance the discussion on hybrid cities by re-examining the values generated by ecosystem services following technological changes. In this paper, we argue that the assumed tradeoff between ecosystem services and technology is inaccurate, since these approaches can be complementary. Indeed, technological change can raise the value of ecosystem services previously ignored, generate a demand for new services, or create new services entirely. Urban systems will reveal more opportunities to integrate complementary ecological designs, simply because urban areas are focal points for built infrastructure. At the same time, there is no reason to believe that the degree of complementarity is greater in urban areas than in rural ones. In the next section, we motivate the study of ecosystem services in urban settings. Then, we review the relationship between ecosystem services and technology, with reference to a historic debate regarding the substitutability of natural and manufactured capital. While many scholars have already accepted the built and natural environment as

1147

complementary, this debate remains relevant as it has framed the discussion on ecosystem services, and constrained its application in technologically advanced settings. Next, we provide a case study in which we examine how new water treatment technologies in Barcelona, Spain altered the mix and value of ecosystem services found there. We trace the value of three ecosystem services: water quality protection, thermal regulation, and nutrient cycling before and after technological change. Finally, we extrapolate lessons from the case and discuss the broader implications for research on ecosystem services in nonpristine environments. Emphasizing that technology and human choice mediate the supply of ecosystem services amends our common conception of natural capital and the services they provide. Ecosystem services are not intrinsic functions of the natural environment, fixed, distant, and removed from society. Rather the supply and value of ecosystem services are linked to human choices and technological change, and therefore in constant evolution. Yet the idea of a fixed supply of ecosystem services, steadily decreasing or deteriorating, has been enshrined as a central tenet in the field (e.g., Schro¨ter et al. 2005; Millennium Ecosystem Assessment 2005; Liu et al. 2010). Discussions about a decreasing supply of ecosystem services overlook our fluid relationship with ecosystem services in the context of technological change. Too frequently, we ignore the possibility that human choice will alter which ecosystem functions are valuable. Recognizing that the supply of ecosystem services is not fixed opens the possibility of uncovering new ecosystem services in the future. Furthermore, the malleable value generated by ecosystems implies that the study of ecosystem services will remain relevant in technologically advanced societies, independent of the technological choices made. Therefore, our argument addresses both technological optimists and skeptics alike. For the technological optimists, the complementary feature of ecosystems reaffirms that the benefits of technological progress will ripple out to society in innovative and unexpected ways. While for the technological skeptics, we highlight the enduring relevance that ecosystems will have in a technologically advanced future.

Urban Ecosystem Services Ecologists have a long history of studying urban ecosystems (Sanders 1984; McDonnell and Pickett 1990; Forman 1995). Abandoned lots, train tracks, city parks, and parking lots provide unique conditions for ecologists to test theories about adaptation, selection, or island biogeography. And the insight from urban ecology has generated practical guidelines for managing ecosystems in cities.

123

1148

Urban ecosystems provide multiple services for their human inhabitants (Go´mez-Baggethun and Barton 2013). Urban ecologists have documented how urban street trees capture carbon, dampen noise, and moderate summer heat; while parks offer places to play, and wetlands process waste (Forman 1995; Bolund and Hunhammar 1999). City street trees in Chicago are estimated to capture 17 metric tons of C/ha year while urban forests in Oakland, California capture 11 metric tons of C/ha year (Pickett et al. 2001). Urban rivers cycle nutrients, and reduce the likelihood of flooding (Grimm et al. 2005; Lundy and Wade 2011). Urbanization and land use change may lead to a decline in ecosystem structures and functions, and their related ecosystem services (McDonald et al. 2013). For example, in a study in San Antonio, Texas, researchers examined the effects of urban sprawl on ecosystem service provision. They estimated that urbanization led to a 4 % net decline in the value of ecosystem services because of the conversion of rangelands, forests, and cropland to urban areas between 1976 and 1991 (Kreuter et al. 2001). Urbanization has also been found to reduce the capacity of streams to process nutrients (Meyer et al. 2005; Grimm et al. 2005). The suite of services lost in urban rivers, and streams are a central feature of the ‘‘urban stream syndrome’’ (Walsh et al. 2005). Urbanization can change the demand for ecosystem services in addition to reducing their supply. The demand for ecosystem services has received less attention than the study of their supply (Honey-Rose´s and Pendleton 2013). A demand-oriented research agenda on ecosystem services invites us to take a closer look at how city dwellers are benefitting from ecosystem structures and functions. Urban and suburban growth increases population densities, increasing the demand for services related to water purification, flood control, recreation, and food production, among others. A study in the Leipzig–Halle region of Germany found that between 1990 and 2007, urban growth increased the demand for ecosystem services, especially in rural and suburban areas (Kroll et al. 2012). Modeling the impact of future land use changes on the spatial distribution of ecosystem services remains challenging, because projected land use changes will alter both supply and demand simultaneously (Eigenbrod et al. 2011). More recently, landscape architects and urban planners have studied how ecological processes can be integrated into cities with urban designs that include solar panels, green roofs, or rain gardens. Green roofs improve storm water management, moderate building temperature, reduce the urban heat island effect, and provide habitat for wildlife (Oberndorfer et al. 2007; Wong and Chen 2009; Pickett et al. 2013). Lundy and Wade (2011) propose ‘‘designingin’’ ecosystem services into urban water management

123

Environmental Management (2014) 53:1146–1157

through the restoration of urban rivers. Thus, the new language of ecosystem services and ‘‘green infrastructure’’ is increasingly being adopted by urban planners and city managers (Tzoulas et al. 2007). A survey of city arborists finds that managing green areas for their ecosystem services has become a new priority, and that maximizing these services for local residents is beginning to take precedence over more traditional goals in urban forestry (Young 2010). In Barcelona, the City Government has recently commissioned a study to quantify the ecosystem services generated by urban forest structures. Using the Urban Forest Effects Model from the US Forest Service, they found that street trees in Barcelona helped improve air quality, sequester carbon, reduce noise, and moderate the urban heat island effect (Chaparro and Terrades 2009). City planners are enthused about the potential to integrate green infrastructure and ecosystem services into their designs. In a provocative attempt to advance the notion of a hybrid city, Beatley (2011) has invited planners to imagine what a ‘‘biophilic city’’ might look like; a city abundant with nature and ‘‘which repairs, restores, and creatively inserts nature wherever it can’’ (Beatley 2011). However, one should not forget the unintended or negative consequences of ecosystem processes—or ‘‘ecosystem disservices’’. Ecosystems are not always benevolent, but can also be unpleasant or dangerous. Urban ecosystem ‘‘disservices’’ might include allergens, invasive species that eliminate native organisms, the hosting of pathogens and pests, the obstruction of mobility, and an increase in greenhouse-gases (Pataki et al. 2011).

Ecosystem Services and Technology Technology has always mediated our relationship with ecosystems, and the services they provide. Tools and instruments of various kinds have allowed humans to extract the benefits generated by ecosystems for centuries. Irrigation techniques helped the ancient Egyptians harness water from the Nile and boost agricultural production sometime around 3000 BC (Worster 1985). Similarly, mechanical farming has helped to increase crop production (Aldy et al. 1998; Raudsepp-Hearne et al. 2010). Yet in the literature on ecosystem services, technological change is often perceived as a substitute for nature’s services. The well-known example of water purification services for New York City (Daily and Ellison 2002), or wastewater treatment with wetland ecosystems instead of municipal treatment (Bolund and Hunhammar 1999) are the clearest illustrations of this substitution. In these cases, choosing to rely on natural capital instead of hard infrastructure implied a smaller capital investment and lower maintenance costs (Chichilnisky and Heal 1998). Yet even

Environmental Management (2014) 53:1146–1157

when the ecosystem management has been chosen over built infrastructure, cities still rely on built infrastructure for the provision of water services, underscoring that the environmental and technological systems must work in concert. While natural and built capital may be mutually reinforcing, ecosystems have the advantage of being more complex and self-sustaining (Ehrlich and Mooney 1983; Costanza 2003). It has been suggested that technology is an inadequate replacement for ecosystems because engineered systems lack the multi-functionality and connectivity of natural systems (Moberg and Ro¨nnba¨ck 2003). Ecosystems provide many services simultaneously, while a technology is usually designed for only one (Raudsepp-Hearne et al. 2010). A wetland can treat wastewater and provide species habitat, or offer recreational opportunities and produce esthetic value. In an urban context, wetlands, detention ponds, and rain gardens may provide multiple ecological and cultural services, while a manufactured storm water system is designed for the singular service of evacuating urban runoff. Or when shrimp farmers convert mangroves to pools for aquaculture, they trade several ecosystem services for the singular service of food production (Barbier et al. 2008). These examples show us that the direction of the substitution matters greatly. The field of ecosystem services doubts technology’s ability to substitute for ecosystems, and yet champions ecosystems over technology. Perhaps the case that has most contributed to our mental juxtaposition of nature versus technology was New York City’s decision to rely on watershed purification services instead of engineered filtration—a decision that saved the city an estimated $4.5 billion, plus $300 million in maintenance expenses (Chichilnisky and Heal 1998). This celebrated example thrust the notion of ecosystem services into the spotlight for the research community and popular press (New York Times 2004; Guterl 2005). New York’s management of ecosystem services generated the expectation that other municipal governments, or even private businesses, would be able to adopt similar ecosystem-based strategies with comparable financial outcomes. More than a decade later, however, neither these expectations have been met; nor has the success from New York’s experience been replicated in other cities (McCauley 2006). One reason was that by the late 1990s, most municipal water suppliers had already installed the expensive filtration system that New York avoided (National Research Council, NRC 2000). With the filtration technology already in place, ecosystem management was no longer deemed an option for most cities to meet drinking water standards, nor would it provide tangible economic benefits. This outcome fed the idea that relying on ecosystem services may be viable in pristine contexts, such as the Catskill Mountains in upstate New York, but has a limited potential in technologically

1149

advanced landscapes, such as those municipalities that had already installed the water filtration systems. This conclusion also captures our intuitive sense that the management of ecosystem services is appropriate for pristine ecosystems, but once the engineered system is installed; there is no reason to return to ‘‘primitive’’ methods of ecosystem management. The loss of natural capital or the superiority of the engineered system was the reason it was installed in the first place. According to this view, in technologically sophisticated environments, ecosystem services simply cannot compete. Thus many assume that our reliance on ecosystem services is temporary until an engineered alternative is found—one that might be more efficient, cost-effective, or both—at which point, resource users will switch to the designed systems instead. And the switch to engineered systems has frequently been motivated by the degradation of well-functioning ecosystems. For instance, engineers developed water treatment technologies in the nineteenth century because of increasing pollution in rivers and lakes (Melosi 1999; Schneider 2011). In these circumstances, the value of ecosystem services becomes more salient after they are lost. However, even in circumstances in which ecosystems are functioning adequately, technological innovation may develop the means to provide superior services. Consider the case in Gramercy, Louisiana, where a wetland processed wastewater from Zapp’s Potato Chip Plant. The tertiary waste water treatment services provided by the wetland were initially valued at $215,220 ($34,700/acre) (Sagoff 2011). However, when the waste emitted from the plant exceeded the wetland’s treatment capacity, the company worked with their congressional representative to secure a federal earmark to build a ‘‘major high-tech waste treatment facility’’ (Sagoff 2011). In this case, the value of the ecosystem service was tied to the absence of a particular technology. Once the technological conditions changed, the wetland could not be valued in the same way, nor be attributed the value of $34,700/acre. While the wetland certainly provided other services, those that generated the most value were substituted by the designed system. Furthermore, this example illustrates that how ecosystem services do not exist unless they are used by or benefitting people. Another example would be ecosystem services associated with coastal protection, whereby biological structures such as mangrove forests, salt marshes, seagrass beds, and coral reefs attenuate waves, with built and gray infrastructure (Koch et al. 2009). Similarly, technological innovation can motivate a switch away from natural systems. Take for example, the case of almond growers in California, who rely on pollination services from bees, even though nearby citrus growers keep the same bees away from their fields because

123

1150

cross pollination causes undesirable features in citrus fruit. If science were to develop new genetically modified almond varieties capable of self-pollination, both almond and citrus farmers might switch away from bee pollination (Sagoff 2011). Once again, the values of the pollination services for both growers are situated within their current technological contexts. The possibility that new technology will eventually substitute for services provided by ecosystems has led authors to criticize the field for being naı¨ve, or offering solutions that will be ineffective in the long run. In a highly cited piece from Nature, McCauley (2006, p. 28) makes the case that ‘‘conservation based on ecosystem services commits the folly of betting against human ingenuity. The entire history of technology and human ‘progress’ is one of producing artificial substitutes for what we once obtained from nature, or domesticating once-natural services… I would argue that conservation plans that underestimate the technological prowess of humans are bound to have short life spans.’’ According to this view, ecosystems are unlikely to remain competitive with technological improvements because humanity will always be discovering better ways to meet our needs. These authors emphasize a tradeoff between services generated by ecosystems and those offered by technological substitutes (McCauley 2006; Sagoff 2011). Fossil fuel-based technologies in particular have allowed society to substitute for ecosystem services, with synthetic fertilizers replacing manure, water treatment systems replacing the capacity for self purification of rivers and lakes, or engineered structures replacing natural flood and erosion control processes (Moberg and Ro¨nnba¨ck 2003; Raudsepp-Hearne et al. 2010). Self proclaimed ‘‘technological optimists’’ assert that human progress can be decoupled from ecological conditions entirely, and that this substitution may continue as long as innovation outpaces environmental degradation (Goeller and Weinberg 1976; Small and Jollands 2006). Neoclassical economic theory originally made the simplifying assumption that natural capital could be substituted for other production inputs including manufactured capital (Go´mez-Baggethun et al. 2010). As evidence of this neoclassical position, scholars often cite the following quote from Robert Solow: ‘‘If it is very easy to substitute other factors for natural resources, then there is in principle no ‘problem’. The world can, in effect, get along without natural resources, so exhaustion is just an event, not a catastrophe’’ (Solow 1974, p. 11). However, this statement is taken out of context, since Solow argues that there are degrees of substitution, not perfect substitution. A central contribution from ecological economics has been highlighting the limits to substitution and the irreplaceability of many forms of natural capital (Costanza and Daly 1992; Cleveland and Ruth 1997; Stern 1997; Go´mez-Baggethun

123

Environmental Management (2014) 53:1146–1157

et al. 2010). Ecological economists have pointed out that manufactured capital will not be able to substitute for natural capital indefinitely because our economic system is embedded within the limits of the natural world. It is unlikely, for example, that manufactured capital will be able to replace lost biodiversity. Costanza and Daly (1992) were the first to posit that natural and manufactured capital were complementary, rather than substitutes: ‘‘For any given level of technical knowledge, human made capital and natural capital are, in general, complements, not substitutes’’ (Costanza and Daly 1992). However, this observation was made against the backdrop of the debate between technological optimists and skeptics. Therefore, the substitution moved in one direction: trading natural capital for manufactured capital. This paper takes this proposition one step further: even when sophisticated technology has already been installed, either to replace ecosystem functions, or isolate managers from the uncertainty associated with ecosystems, natural capital will remain complementary to technological change. That is, the complementarity will remain for the very ecosystems that are affected by the technological change. Furthermore, the mix of services used in the future will be different than today, with some ecosystem services being created by the new tools, machines, or materials that we use in the future. In the case study that follows, we examine how a major technological improvement at two drinking water facilities changed the value of ecosystem services found upstream. We find that technology and ecosystem services remain complementary even after the high-tech membrane system was installed.

Case Study: Water Treatment Technologies in Barcelona, Spain The city of Barcelona relies on surface water from the Llobregat River for nearly 50 % of its drinking water (Mujeriego 2006). Two treatment facilities withdraw water from the river (Fig. 1). The Aigu¨es Ter-Llobregat (ATLL) facility in Abrera, Spain is a public water treatment wholesaler that supplies municipal providers. Downstream, a second water treatment facility is owned and operated by the private water company Aigu¨es de Barcelona (AGBAR) in Sant Joan Despı´ (SJD). Between 2008 and 2010 both treatment plants simultaneously improved their treatment process by adding new desalination membranes. ATLL purchased electrodialysis reversal (EDR) technology (Valero and Arbo´s 2010) while AGBAR installed reverse osmosis membranes (Luque 2008). This technological improvement was motivated by new drinking water quality standards that reduced the permissible level of total trihalomethanes to below 100 lg/L (Royal Decree, RD 2003).

Environmental Management (2014) 53:1146–1157

Fig. 1 The city of Barcelona largely relies on water from the Llobregat River for its drinking water supply. Two major water treatment facilities draw water from river. Mine tailings in the mid section of the watershed are a major source of salinity in the Llobregat River

In order to comply with the new regulation, water treatment managers concluded that desalination technology was necessary. The surface waters from the Llobregat River are mineralized, with an especially high concentration of salts and bromine (Fernandez-Turiel et al. 2003). These pollutants enter the river through surface or groundwater flows that come into contact with the large mountains of salt deposited by an extractive potash industry upstream (ATLL 2008; Luque 2008). The cause of the Llobregat’s salinization was initially disputed by the mining companies, since the natural geology of the watershed contains the same minerals polluting the river. However, a historical review (Honey-Rose´s 2012) as well as an analysis using isotope tracers has linked the mineralization of the Llobregat River with industrial processes from the potashmining industry (Otero and Soler 2002). The Llobregat has other pollution problems typical in urban settings. River impairment is more acute in the lower reaches, where there is heavy nutrient loading, turbidity, and thermal heating.

Advanced Membrane Technologies for Water Treatment In 2009, the ATLL treatment facility installed an EDR desalination system to remove bromine, the critical precursor to trihalomethanes, and to ensure compliance with the new water quality standards. Dissolved ionic bromines are problematic for water treatment managers because they

1151

contribute to the formation of trihalomethanes during the water treatment process when mixed with chlorine (Sorlini and Collivignarelli 2005). The concentrations of trihalomethanes in drinking water supplies are regulated because they are carcinogenic (Villanueva-Belmonte 2003), and higher water temperatures accelerate the formation of trihalomethanes (Toroz and Uyak 2005). Disinfection byproducts such as trihalomethanes are usually removed by modifying the chlorine process or removing the chlorine sensitive compounds (Gopal et al. 2007). Together with an expansion in treatment capacity, the new system costs over €61 million (Valero and Arbo´s 2010). EDR technology separates dissolved ions such as Br-, Cl-, and Na? by applying electrical charges. The membranes reverse polarity between positive and negative charges every 20 min to clean the membranes and reduce fouling incidents (American Water Works Association, AWWA 1995). When the EDR system was installed, it was the largest of its type in the world. Simultaneously, the second water treatment plant managed by AGBAR installed an ultrafiltration and reverse osmosis system at their facility in SJD. In comparison with older technologies, reverse osmosis marks a clear departure from the traditional municipal water treatment systems that dominated the twentieth century. While EDR and reverse osmosis technologies differ, both water treatment plants share several features. First, and most obviously, both systems adopt advanced desalination membrane systems that are expensive to install and operate. Second, the new membranes did not replace the older system, but were appended onto the pre-existing chain of treatment technologies. Last, and most importantly for our study of ecosystem services, the new treatment technologies significantly altered the cost structure of the treatment process. The new membrane systems incorporated two new water quality parameters into the treatment cost function: (1) salinity, as measured by conductivity (lS/cm), and (2) temperature (C). Both of these water quality parameters became critical determinants of water treatment costs once the new system began to operate. By choosing to install new water treatment systems downstream, water managers revealed their preference for technological strategies over ecosystem approaches for improving source water quality. And with the new sophisticated treatment system, they attained the capacity to meet output water quality standards across a much wider range of input water qualities. Therefore, at first glance, the sophisticated new technology further isolated managers from the influence of ecosystem processes. To assess the impact of technological change on the value of ecosystem services, we analyzed three ecosystem services: water quality protection (affecting salinity); thermal regulation (affecting temperature); and nutrient cycling (affecting

123

1152

The Value of Ecosystem Services Following Technological Change

1.00

Energy Efficiency (kWh/m3)

ammonium), before and after the adoption of new membrane treatment.

Environmental Management (2014) 53:1146–1157

0.80 0.60 0.40 0.20 0.00

Water Quality Protection and Salinity The new EDR water treatment technology was adopted to reduce the uncertainty surrounding freshwater provision, and yet this installation created new linkages with ecosystem functions. Prior to the installation of the desalination systems, treatment costs were impervious to fluctuations in salinity, largely because the traditional treatment methods were incapable of removing chloride ions from the feed water. In the past, water managers did not modify their treatment process in response to fluctuating salinity values. The exception was when salinity values passed maximum permissible concentrations, in which case, surface water treatment was stopped altogether. These high concentrations usually occurred when the brine collector that transports mining effluents from the mines to the Mediterranean would rupture and release highly concentrated salt water directly into the river. However, following the installation of the new membranes, salinity became a significant driver of treatment costs. For reverse osmosis systems, the cost of removing salts is governed by the laws of osmotic pressure. In order to quantify the newly created marginal benefits associated with salinity reductions, we estimated reduced treatment costs associated with potential reductions in salinity in the Llobregat River with the Reverse Osmosis System Analysis (ROSA) software (version 7.2.7), created by Dow Chemical (2011), the membrane manufacturer. ROSA allowed us to configure a desalination system with the specification of AGBAR’s treatment plant in SJD. We ran ROSA with different salinity concentrations and observed how much energy was needed to maintain the same system performance. As expected, higher concentrations of salt required more energy/m3 of water produced (Fig. 2). When the feed water has higher salinity concentrations, marginal water quality improvements produce more energy savings than the same marginal improvements in cleaner water. The Llobregat River has an average conductivity of 1,500 lS/ cm. At this reference point, a reduction of 100 lS/cm would save AGBAR approximately €159,612/year. The installation of new membrane technologies produced similar changes to treatment costs at the ATLL treatment plant. Lower salinity levels in the Llobregat River would allow ATLL to produce the same quality drinking water with less electrical current running through the EDR modules. To quantify the potential savings

123

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Conductivity (µS/cm)

Fig. 2 The conductivity (lS/cm) and specific energy efficiency (kWh/m3) relationship for the LE-440i reverse osmosis membranes produced by Dow Chemical and used by AGBAR in Sant Joan Despı´. Y = 0.313e0.0005x. R2 = 0.9988

Fig. 3 The observed relationship between conductivity (lS/cm) and energy consumed (kWh/m3) for the EDR water treatment system operated by ATLL in Abrera. Y = 0.0002x ? 0.1481. R2 = 0.2586

associated with salinity reductions, we observed the conductivity–energy (kWh/m3) relationship at nine EDR modules operating in November 2010 and July 2010 (n = 247). For every unit increase in conductivity (lS/cm), the treatment system consumed on average an additional 0.0002 kWh/m3 (Fig. 3). This implies that a reduction in conductivity of 100 lS/cm would be associated with an increase in energy use of 0.02 kWh/m3. ATLL annually produces approximately 30 million cubic meters of drinking water with the EDR system. The energy expenses associated with this production are approximately €939,600/year with a mean energy expenditure of 0.348 kWh/m3 and an average energy cost of 0.09 €/kWh. Under these conditions, a reduction in conductivity by 100 lS/cm would generate savings of €54,000/ year for the ATLL treatment plant. The installation of the membrane technology has realigned economic incentives for both water treatment facilities. With the new desalination systems, water treatment managers now have an incentive to invest in ecosystem structures or functions that can protect the river from salt pollution. One approach for reducing salinity concentrations is to restore the mountains of mine tailings with halophytic vegetation. A restored ecosystem covering the salt mountains would help protect the water quality of the Llobregat River by reducing the volume of water coming into contact with the salt deposits

Environmental Management (2014) 53:1146–1157

1153

Table 1 Treatment costs savings associated with reductions in conductivity (lS/cm) at both treatment plants with their respective desalination technologies Mean daily reductions in feed water conductivity (lS/cm)

Reduced treatment cost AGBAR (€)

Reduced treatment cost ATLL (€)

Total savings/ year (€)

100

159,612

54,000

213,612

200

272,321

108,000

387,321

300

399,030

162,000

561,030

400

518,740

216,000

734,740

500

598,546

270,000

868,546

Conductivity reductions depart from a baseline value of 1,500 lS/cm

and filtering into the groundwater. Restoring vegetation on these salt mountains would require specialized techniques, since most plant life is anathema to salty soils. However, halophyte species that are tolerant to saltier soils may be candidates for restoration (Adams et al. 1998; Bohnert and Cushman 2000). Despite inhospitable soil conditions, we see evidence that the salt deposits in the area can be restored with living vegetation. In the 1960s, environmental groups and the mining company collaborated to cover the abandoned Botjosa salt tailings with soil and seeds. The initial planting had difficulties, but some vegetation has survived, and the results of this project remain visible today (Honey-Rose´s 2012). In addition, the local water agency has initiated projects to restore the mine tailings that are expected to reduce stormwater/groundwater interactions (Age`ncia Catalana del Agua 2009). Based on the salinity–energy relationships presented above, we estimate the benefits that restoration projects could produce for the water treatment managers downstream. For example, given current conductivity of 1,500 lS/cm, a reduction in mean daily conductivity values in the Llobregat River by 100 lS/cm would generate ecosystem services worth €213,612/year. A reduction of conductivity by 500 lS/cm would generate services worth €868,546/year (Table 1).

Thermal Protection and Temperature Stream temperature is another water quality parameter inserted into the cost function following the adoption of the new treatment technology. Given that trihalomethanes form more rapidly during warmer months (Toroz and Uyak 2005), water managers at the ATLL facility turn on additional EDR modules as stream temperatures rise in the spring and summer (ATLL 2008). Every additional EDR module costs approximately €1,000/day to operate. Stream temperature controls critical ecosystem processes such as the metabolic rates of aquatic species (Acun˜a and Tockner 2009). Warm temperatures also

reduce the solubility of oxygen, and low concentrations of dissolved oxygen make waters less hospitable to fish and invertebrates (Graczyk and Sonzogni 1991). Thermal heating is symptomatic of urbanized watersheds and modified river systems (Webb et al. 2008). Stream temperatures can be moderated with the restoration of riparian forest or increases in stream discharge (Bartholow 1991). ATLL’s reliance on stream temperature to guide operation decisions has created a link between the ecological condition of the Llobregat River and operating costs at the treatment plant. A restored riparian habitat that reduces stream temperature would also reduce the days in which EDR modules operate. Depending on the extent of the forest restoration, the restoration of riparian vegetation could provide ecosystem services in the range of €57,000– €156,000/year (Honey-Rose´s et al. 2013). This specific value generated by the riparian forests would not exist in the absence of the EDR treatment. Increasing stream discharge and restoring floodplains could have a similar cooling effect on stream temperatures, and reduce treatment expenses further. Similar to the circumstances found with salinity, the adoption of the EDR technology created a new incentive for ATLL managers to explore ecosystem management practices that would restore ecological functions and reduce thermal heating in the Llobregat River. Nutrient Cycling and Ammonium The marginal value of nutrient cycling services may also increase following the installation of new treatment technologies. Nitrification services are valuable for water managers at the AGBAR–SJD water treatment facility, because they are frequently forced to halt treatment when the Llobregat River fails to meet minimum water quality standards (Lloret 2004). Ammonium concentrations are especially problematic, because they often exceed the maximum permissible values for treatable water. Between 2000 and 2010, high ammonium concentrations forced AGBAR to stop treatment on 286 occasions (Fig. 4). Stoppage events generate a penalty cost because they oblige the treatment company to purchase water at a higher cost elsewhere. Ammonium is released into the Llobregat River and its tributaries primarily by wastewater treatment plants. The concentrations rise during wet weather events because of combined sewer overflows that release untreated wastewater into the river. Ammonium concentrations are also high during winter months when the colder temperatures slow down the bacterial nitrification of ammonia (Mujeriego 2006). With the new membrane treatment technology, AGBAR has the ability to treat water with higher ammonium concentrations and still meet water quality standards. Thus, treatment managers have been studying the possibility of

123

1154

Environmental Management (2014) 53:1146–1157

Fig. 4 Ammonium concentrations at the AGBAR– SJD water treatment facility from January 1, 2000 to December 31, 2010. The line at 2.5 mg/L marks the treatment stoppage threshold. Total exceedance days in 11 years: 286 (7.1 %)

increasing the stoppage threshold for ammonium. Currently, the stoppage threshold is at 2.5 mg/L. If the treatment managers raise the stoppage threshold, then they could continue to treat water at higher ammonium concentrations. Ecosystem processes play a critical role in determining the concentration of ammonium in the Llobregat River. Nitrification occurs in the river’s soils or other surfaces where biofilms accumulate (Butturini et al. 2000), and streams that are impaired have lower nitrification rates than rivers in good ecological condition (Martı´ et al. 2004). Restoration measures such as recovering meanders, widening flood plains, hyporheic restoration, or revegetation can increase instream nitrification and denitrification (Admiraal and Botermans 1989; Kaushal et al. 2008). Nitrification coupled with denitrification leads to the removal of N from the aquatic system. In the case of the Llobregat, river restoration measures would be particularly valuable because higher nitrification rates could also reduce the number of days in which water treatment is stopped, and penalty costs are incurred. With a higher ammonium threshold, it would first appear that the cumulative value of instream nitrification services would be reduced. An analysis using hourly data on ammonium concentrations from 2000 to 2010 shows that under these new circumstances; however, the value of investing in nitrification services may increase or decrease, depending on where the new threshold is located (HoneyRose´s 2012). Unexpectedly, once a new technology has allowed water treatment managers to raise the stoppage threshold to a higher level, the same investment in ecosystem services might be worth more with the technology than without. This makes intuitive sense if one can imagine the new (higher) stoppage treatment threshold being located just below a cluster of peak ammonium values.

Discussion Urban environments provide new opportunities to discover and manage ecosystem services. In the case of water

123

treatment in Barcelona, the new membrane technologies did not eliminate the demand for ecosystem services associated with water purification. To the contrary, several ecosystem services that regulated water quality became more valuable. Water treatment managers installed the new membrane systems to allow for more continuous treatment across a wider range of input water qualities—in essence, protecting themselves from ecosystem variability and uncertainty. And yet unexpectedly, the new technology created additional reasons to invest in ecosystem management. In some circumstances, technological change may reduce our reliance on natural processes. Water filtration systems have reduced our reliance on watershed services associated with soil and sediment retention, and chlorination has reduced our reliance on natural processes that eliminate infectious bacteria. These technological advancements have created unquestionable benefits for society. However, less attention has been directed at how ecosystem management may complement the new technologies once they already have been adopted. Of course, technological change will not always increase the value of ecosystem services. Recall the case from Gramercy, Louisiana, where the wetlands lost much of their monetary value following the installation of a wastewater treatment facility. As technology changes, so too will the values we assign to different ecosystem processes. In a more technologically advanced future, the bundle of ecosystem services we use will transform as different technologies favor different sets of ecosystem functions. Ecosystem service values are not static. Rather they are a function of human preferences and our interaction with technology. In Barcelona we observed how new services were generated from existing ecosystem structures and functions because of technological choice. Certainly, the ecosystem structures and functions that protected water quality and reduced stream temperatures existed prior to the membrane technology, but following the membrane technology, these services began to generate specific use values for defined beneficiaries. This paper focuses on use values, but there is

Environmental Management (2014) 53:1146–1157

no reason why this argument cannot be generalized to ecosystem services that generate non-use values. For example, underwater exploration technologies may allow us to view and appreciate submerged life forms previously unknown or unseen, increasing their value to society. Even in the context of non-use values, technology may increase the value of ecosystems and their services. Barcelona’s experience in water treatment suggests that ideas about ecosystem services remain relevant in technologically advanced settings. As we look to solve our global water problems, we should look at both ecological and technological solutions and how they may mutually reinforce one another. Globally, over 1 billion people remain without clean drinking water and approximately 2.3 billion live in water scarce regions (Service 2006). If countries in the developing world leap-frog to advanced water treatment systems to purify their contaminated sources, then the management of ecosystem services must be considered simultaneously as a viable option to improve river ecology and reduce water treatment costs. Even in technologically sophisticated environments, an ecosystem services approach can uncover new management options that may bring both environmental and economic benefits. This paper has sought to underscore the potential of ecosystem management in urban and technologically advanced contexts. The new treatment technologies at ATLL and AGBAR allowed water managers to improve drinking water quality and increased water security. It is difficult to imagine ecosystems providing equivalent improvements in quantity, quality and certainty in such a short period of time. However, the water quality improvements from the new technological systems also came with a considerable financial and environmental cost. Addressing water demands with energy-intensive systems is unlikely to be a sustainable solution in the long run (Mehan 2009). Instead, water managers would do well to explore ecosystem alternatives regardless of their technological circumstances. The mere presence of modern treatment systems should not blind us to opportunities to manage ecosystem services. While technology change may obviate the need for some ecosystem services, new technology will also generate a demand for new services or previously unvalued services. Therefore, the management of ecosystem services will always remain complementary to the adoption of new technologies, and the values ascribed to ecosystems will always depend on the institutional and technological context. Future technologies will rearrange the importance that managers will place on different environmental parameters and services. The rise of new technologies will not reduce our reliance on ecosystem services, but rather ecosystems will benefit us in new and different ways. Regardless of the technological environment the future may hold, investing

1155

in knowledge about ecosystem services will remain a wise development strategy. Acknowledgments This research received funding from the Centre Tecnolo`gic de l’Aigua (CETaqua) and the Age`ncia Catalana de l’Aigua (ACA). The authors thank AGBAR and ATLL for data, and the Catalan Institute for Water Research for general support. The manuscript benefited from conversations with Vicenc¸ Acun˜a, Pedro Arrojo, Mo`nica Bardina, Carlos Campos, Edward Feser, Benoit Lefe`vre, Rafa Marce´, Antoni Munne´, Sergi Sabater, Marta Terrado, ` lex Vega. Montserrat Termes, Joana Tobella, Fernando Valero, and A Three anonymous reviewers provided insightful comments.

References Acun˜a V, Tockner K (2009) Surface-subsurface water exchange rates along alluvial river reaches control the thermal patterns in an Alpine River network. Freshw Biol 54(2):306–320. doi:10.1111/ j.1365-2427.2008.02109.x Adams P, Nelson DE, Yamada S, Chmara W, Jensen RG, Bohnert HJ, Griffiths H (1998) Tansley Review No. 97. Growth and development of Mesembryanthemum crystallinum (Aizoaceae). N Phytol 138:171–190 Admiraal W, Botermans YJH (1989) Comparison of nitrification rates in three branches of the lower Rhine. Biogeochemistry 8:135–151 Age`ncia Catalana del Agua (2009) Projecte constructiu de les actuacions destinades a la reduccio´ de l’impacte ambiental del runam inactiu de Vilafruns. Generalitat de Catalunya. Departament de Medi Ambient i Habitage, Barcelona Aigu¨es Ter-Llobregat, ATLL (2008) Estudi per a l’optimitzacio´ econo`mica-sanita`ria del funcionament conjunct del tractament convencional i la instal.lacio´ d’electrodia`lisis reversible a l’ETAP del Llobregat (T.M. Abrera). Planificacio´ del servei de produccio´ d’aigua per al consum huma`. Aigu¨es Ter Llobregat, Abrera Aldy JE, Hrubovcak J, Vasavada U (1998) The role of technology in sustaining agriculture and the environment. Ecol Econ 26:81–96. doi:10.1016/S0921-8009(97)00068-2 American Water Works Association, AWWA (1995) Electrodialysis and electrodialysis reversal. AWWA Manual M38. Denver Armsworth PR, Chan KMA, Daily GC, Ehrlich PR, Kremen C, Ricketts TH, Sanjayan MA (2007) Ecosystem-service science and the way forward for conservation. Conserv Biol 21(12): 1383–1384. doi:10.1111/j.1523-1739.2007.00821.x Bai Y, Zhuang C, Ouyan Z, Zheng H, Jiang B (2011) Spatial characteristics between biodiversity and ecosystem services in a human-dominated watershed. Ecol Complex 8:177–183. doi:10. 1016/j.ecocom.2011.01.007 Barbier EB, Koch EW, Silliman BR, Hacker SD, Wolanski E, Primavera J, Granek EF et al (2008) Coastal ecosystem-based management with nonlinear ecological functions and values. Science 319:321–323. doi:10.1126/science.1150349 Bartholow JM (1991) A modeling assessment of the thermal regime for an urban sport fishery. Environ Manag 15(6):833–845. doi:10.1007/BF02394821 Beatley T (2011) Biophilic cities: integrating nature into urban design and planning. Island Press, Washington, DC Bohnert HJ, Cushman JC (2000) The ice plant cometh: lessons in abiotic stress tolerance. J Plant Regul 19:334–346 Bolund P, Hunhammar S (1999) Ecosystem services in urban areas. Ecol Econ 29(2):293–301. doi:10.1016/S0921-8009(99)00013-0 Butturini A, Battin TJ, Sabater F (2000) Nitrogen in stream sediment biofilms: the role of ammonium concentrations and DOC quality. Water Resour 34(2):629–639. doi:10.1016/S0043-1354(99)00171-2

123

1156 Chaparro L, Terrades J (2009) Ecological Services of Urban Forest in Barcelona. Centre de Recerca Ecolo`gica i Applicacions Forestals. Universitat Auto`noma de Barcelona. Bellaterra, Spain. 103 pgs Chichilnisky G, Heal G (1998) Economic returns from the biosphere. Nature 391:629–630 Cleveland CJ, Ruth M (1997) When, where and by how much do biophysical limits constrain the economic process? A survey of Nicholas Georgescu-Roegen’s contribution to ecological economics. Ecol Econ 22(3):203–223 Costanza R (2003) A vision of the future of science: reintegrating the study of humans and the rest of nature. Futures 35:651–671 Costanza R, Daly HE (1992) Natural capital and sustainable development. Conserv Biol 6(1):37–46 Daily GC (1997) Nature’s services. Island Press, Washington, DC Daily GC, Ellison K (2002) The new economy of nature. Island Press, Washington, DC Dow Chemical (2011) Reverse Osmosis System Analysis (ROSA) 7.2.7. http://www.dowwaterandprocess.com/support_training/ design_tools/rosa.htm. Accessed 18 March 2014 Ehrlich PR, Mooney HA (1983) Extinction, substitution, and ecosystem services. Bioscience 33:248–254 Eigenbrod F, Anderson BJ, Armsworth PR, Heinemeyer A, Jackson SF, Parnell M, Thomas CD, Gaston KJ (2009) Ecosystem service benefits of contrasting conservation strategies in a humandominated region. Proc R Soc B 276(1669):2903–2911. doi:10. 1098/rspb.2010.2754 Eigenbrod F, Bell VA, Davies HN, Heinemeyer A, Armsworth PR, Gaston KJ (2011) The impact of projected increases in urbanization on ecosystem services. Proc R Soc B 278(1722): 3201–3208 Ellin N (2013) Integral Urbanism: a context for urban design. In: Pickett STA et al (eds) Resilience in ecology and urban design: linking theory and practice for sustainability. Springer, London, pp 63–78 Fernandez-Turiel JL, Gimeno D, Rodriguez JJ, Carnicero M, Valero F (2003) Spatial and Seasonal Variations of water quality in a Mediterranean catchment: the Llobregat River (NE Spain). Environ Geochem Health 25(4):453–474. doi:10.1023/B:EGAH. 0000004566.75757.98 Fisher B et al (2011) Measuring, modeling and mapping ecosystem services in the Eastern Arc Mountains of Tanzania. Prog Phys Geogr 35(5):595–611. doi:10.1177/0309133311422968 Forman RTT (1995) Land mosaics. Cambridge University Press, Cambridge Goeller HE, Weinberg AM (1976) The age of substitutability. Science 20:683–689 Goldstein JH (2007) Paying for conservation in human dominated landscapes. Dissertation, Stanford University, Stanford Go´mez-Baggethun E, Barton DN (2013) Classifying and valuing ecosystem services for urban planning. Ecol Econ 86:235–245. doi:10.1016/j.ecolecon.2012.08.019 Go´mez-Baggethun E, de Groot R, Lomas PL, Montes C (2010) The history of ecosystem services in economic theory and practice: from early notions to markets and payment schemes. Ecol Econ 69:1209–1218. doi:10.1016/j.ecolecon.2009.11.007 Gopal K, Swarupa Tripathy S, Bersilon JL, Prabha Dubey S (2007) Chlorination by products their toxicodynamics and removal from drinking water. J Hazard Mater 140:1–6. doi:10.1016/j.jhazmat. 2006.10.063 Graczyk DJ, Sonzogni WC (1991) Reductions of dissolved-oxygen concentrations in Wisconsin streams during summer runoff. J Environ Qual 20(2):445–451. doi:10.2134/jeq1991.004724 25002000020018x Grimm NB, Sheibley RW, Crenshaw CL, Dahm CN, Roach WJ, Zeglin LH (2005) N retention and transformation in urban

123

Environmental Management (2014) 53:1146–1157 streams. J N Am Benthol Soc 24(3):626–642. doi:10.1899/08873593 Guterl F (2005, 1 June) Investing in green. Newsweek 36 Honey-Rose´s J (2012) Ecosystem services in planning practice for urban and technologically advanced landscapes. Dissertation, Department of Urban and Regional Planning, University of Illinois, Urbana Champaign, Urbana Honey-Rose´s J, Pendleton LH (2013) A demand driven research agenda for ecosystem services. Ecosyst Serv 5:160–162. doi:10. 1016/j.ecoser.2013.04.007 Honey-Rose´s J, Acun˜a V, Bardina M, Brozovic N, Munne´ A, Sabater ` , Schneider DW (2013) S, Termes M, Valero F, Vega A Examining the demand for ecosystem services: the value of stream restoration for drinking water managers in the Llobregat River, Spain. Ecol Econ 90:196–205. doi:10.1016/j.ecolecon. 2013.03.019 Hubacek K, Kronenberg J (2013) Synthesizing different perspectives on the value of urban ecosystem services. Landsc Urban Plan 109:1–6. doi:10.1016/j.landurbplan.2012.10.010 Kareiva P, Watts S, McDonald R, Boucher T (2007) Domesticated nature: shaping landscapes and ecosystems for human welfare. Science 316:1866–1869 Kaushal SS, Groffman PM, Mayer PM, Striz E, Gold AJ (2008) Effects of stream restoration on denitrification in an urbanized watershed. Ecol Appl 18(3):789–804. doi:10.1890/07-1159.1 Koch EW, Barbier EB, Silliman BR, Reed DJ, Perillo GM, Hacker SD, Granek EF, Primavera JH, Muthiga N, Polasky S, Halpern BS, Kennedy CJ, Kappel CV, Wolanski E (2009) Non-linearity in ecosystem services: temporal and spatial variability in coastal protection. Front Ecol Environ 7(1):29–37. doi:10.1890/080126 Kreuter UP, Harris HG, Matlock MD, Lacey RE (2001) Change in ecosystem service values in the San Antonio area, Texas. Ecol Econ 39:333–346. doi:10.1016/S0921-8009(01)00250-6 Kroll F, Mu¨ller F, Haase D, Fohrer N (2012) Rural-urban gradient analysis of ecosystem services supply and demand dynamics. Land Use Policy 29(3):521–535. doi:10.1016/j.landusepol.2011. 07.008 Liu S, Costanza R, Farber S, Troy A (2010) Valuing ecosystem services: theory, practice, and the need for a transdisciplinary synthesis. Ann NY Acad Sci 1185:54–78. doi:10.1111/j.17496632.2009.05167.x Lloret R (2004) La qualitat de l’aigua del riu Llobregat. Un factor limitant del passat, un element clau per al futur. In: Prat N, Tello E (eds) El Baix Llobregat: histo`ria i actualitat ambiental d’un riu. Centre d’estudis Comarcals del Baix Llobregat, Barcelona, pp 92–141 Lundy L, Wade R (2011) Integrating science to sustain urban ecosystems. Prog Phys Geogr 35(5):653–669 Luque F (2008) Tratamiento del Agua del Rı´o Llobregat en la ETAP de Sant Joan Despı´ (Barcelona) por Membranas de Ultra´ smosis Inversa. In: Asociacio´n Espan˜ola de filtracio´n y O Desalacio´n y Reutilizacio´n VII Congreso AEDyR, 3–5 Dec 2008 Martı´ M, Aumatell J, Gode´ L, Poch M, Sabater F (2004) Nutrient retention efficiency in streams receiving inputs from wastewater treatment plants. J Environ Qual 33:285–293. doi:10.2134/ jeq2004.2850 McCauley DJ (2006) Selling out on nature. Nature 443(27–28):27–28 McDonald RI, Marcotullio PJ, Gu¨neralp B (2013) Urbanization and global trends in biodiversity and ecosystem services. In: Pickett STA et al (eds) Resilience in ecology and urban design: linking theory and practice for sustainability. Springer, London, pp 31–52 McDonnell MJ, Pickett STA (1990) Ecosystem structure and function along urban–rural gradients: an unexploited opportunity for ecology. Ecology 71(4):1232–1237. doi:10.2307/1938259 Mehan GT (2009, 4 Feb) Congressional testimony before the Subcommittee on Water Resources and Environment of the

Environmental Management (2014) 53:1146–1157 House Committee on Transportation and Infrastructure on Sustainable Water Management Melosi MV (1999) The sanitary city: urban infrastructure in America from colonial times to the present. The Johns Hopkins University Press, Baltimore Meyer JL, Paul MJ, Taulbee WK (2005) Stream ecosystem functioning in urbanizing landscapes. Journal of the North American Benthological Society 24(3):602–612 Millennium Ecosystem Assessment (2005) Ecosystems and human wellbeing: current states and trends. Island Press, Washington, DC Moberg F, Ro¨nnba¨ck P (2003) Ecosystem services of the tropical seascape: interactions, substitutions and restoration. Ocean Coast Manag 46(1–2):27–46. doi:10.1016/S0964-5691(02)00119-9 Mujeriego R (2006) Abastament d’aigua des del Baix Llobregat nord: Diagnosi per a la millora de la qualitat. Age`ncia Catalana de l’Aigua, Aigues Ter-Llobregat, Direccio´ General de Salut Pu´blica. Generalitat de Catalunya, Barcelona Naidoo R, Ricketts TH (2006) Mapping the economic costs and benefits of conservation. PLoS Biol 4(11):2153–2164.e360. doi:10.1371/journal.pbio.0040360 National Research Council (NRC) (2000) Watershed management for potable water supply: assessing the New York City strategy. National Academy Press, Washington, DC New York Times (2004) Save the watershed. Editorial Desk. Sunday Edition Section 4, Column 1:14 Norgaard RB (2010) Ecosystem services: from eye-opening metaphor to complexity blinder. Ecol Econ 69(6):1219–1227 Oberndorfer E, Lundholm J, Bass B, Coffman RR, Doshi H, Dunnett N, Gaffin S, Kohler M, Liu KKY, Rowe B (2007) Green roofs as urban ecosystems: Ecological structures, functions, and services. Bioscience. 57(10):823–833. doi:10.1641/B571005 Otero N, Soler A (2002) Sulphur isotopes as tracers of the influence of potash mining in groundwater salinisation in the Llobregat Basin (NE Spain). Water Res 36(16):3989–4000. doi:10.1016/S00431354(02)00125-2 Pataki DE, Carreiro MM, Cherrier J, Grulke NE, Jennings V, Pincetl S, Pouyat RV, Whitlow TH, Zipperer WC (2011) Coupling biogeochemical cycles in urban environments: ecosystem services, green solutions, and misconceptions. Front Ecol Environ 9(1):27–36. doi:10.1890/090220 Pickett STA, Cadenasso ML, Grove JM, Nilon CH, Pouyat RV, Zipperer WC, Costanza R (2001) Urban ecological systems: linking terrestrial ecological, physical, and socioeconomic components of metropolitan areas. Annu Rev Ecol Syst 32:127–157 Pickett STA, Cadenasso ML, McGrath B (2013) Ecology of the city as a bridge to urban design. In: Pickett STA et al (eds) Resilience in ecology and urban design: linking theory and practice for sustainability. Springer, London, pp 7–27 Raudsepp-Hearne C, Peterson GD, Tengo¨ M, Bennett EM, Holland T, Benassaiah K, MacDonald GK, Pfeifer L (2010) Untangling the Environmentalist’s Paradox: why is human well-being increasing as ecosystem services degrade? Bioscience 60(8):576–589. doi:10.1525/bio.2010.60.8.4 Royal Decree, RD (2003, 7 Feb) Establishment of Spanish Drinking Water Quality Standards. 2003/140 Sachs JD, Reid WV (2006) Investments toward sustainable development. Science 312(5776):1002 Sagoff M (2011) The quantification and valuation of ecosystem services. Ecol Econ 70(3):497–502. doi:10.1016/j.ecolecon. 2010.10.006

1157 Sanders RA (1984) Some determinants of urban forest structure. Urban Ecol 8(1–2):13–27. doi:10.1016/0304-4009(84)90004-4 Schneider DW (2011) Hybrid nature: sewage treatment and the contradictions of the industrial ecosystem. MIT Press, Cambridge Schro¨ter D et al (2005) Ecosystem service supply and vulnerability to global change in Europe. Science 310(5752):1333–1337. doi:10. 1126/science.1115233 Service RF (2006) Desalination freshens up. Science 313(5790): 1088–1090. doi:10.1126/science.313.5790.1088 Shannon K (2013) Eco-engineering for water: from soft to hard and back. In: Pickett STA et al (eds) Resilience in ecology and urban design: linking theory and practice for sustainability. Springer, London, pp 163–182 Small B, Jollands N (2006) Technology and ecological economics: promethean technology, Pandorian potential. Ecol Econ 56(3): 343–358. doi:10.1016/j.ecolecon.2005.09.013 Solow RM (1974) The economics of resources or the resources of economics. Am Econ Rev 64(2):1–14 Sorlini S, Collivignarelli C (2005) Trihalomethane formation during chemical oxidation with chlorine, chlorine dioxide and ozone of ten Italian natural waters. Desalination 176(1–3):103–111. doi:10.1016/j.desal.2004.10.022 Stern DI (1997) Limits to substitution and irreversibility in production and consumption: a neoclassical interpretation of ecological economics. Ecol Econ 21(3):197–215. doi:10.1016/S0921-8009 (96)00103-6 Toroz I, Uyak V (2005) Seasonal variations of trihalomethanes (THMs) in water distribution networks of Istanbul City. Desalination 176(1–3):127–141. doi:10.1016/j.desal.2004.11.008 Tzoulas K, Korpela K, Venn S, Yli-Pekonen V, Kaz´ierczak A, Niemela J, James P (2007) Promoting ecosystem and human health in urban areas using Green Infrastructure: a literature review. Landsc Urban Plan 81(3):167–178. doi:10.1016/j.land urbplan.2007.02.001 Valero F, Arbo´s R (2010) Desalination of brackish river water using Electrodialysis Reversal (EDR) Control of the THMs formation in the Barcelona (NE Spain) area. Desalination 253(1–3): 170–174. doi:10.1016/j.desal.2009.11.011 Villanueva-Belmonte C (2003) Subproductes de la desinfeccio´ de l’Aigua Potable i Ca`ncer de Bufeta Urina`ria. Dissertation, Universitat Autonoma de Barcelona Walsh CJ, Roy AH, Feminella JW, Cottingham PD, Groffman PM, Morgan RP (2005) The urban stream syndrome: current knowledge and the search for a cure. J N Am Benthol Soc 24(3):706–723 Webb BW, Hannah DM, Moore RD, Brown LE, Nobilis F (2008) Recent advances in stream and river temperature research. Hydrol Process 22:902–918. doi:10.1002/hyp.6994 Wong NH, Chen Y (2009) Tropical Urban Heat Islands: climate, buildings and greenery. Taylor and Francis, London Worster D (1985) Rivers of empire. Water, aridity, and the growth of the American west. Oxford University Press, New York Wunder S (2007) The efficiency of payments for environmental services in tropical conservation. Conserv Biol 21(1):48–58. doi:10.1111/j.1523-1739.2006.00559.x Young RF (2010) Managing municipal green space for ecosystem services. Urban For Urban Green 9(4):313–321. doi:10.1016/j. ufug.2010.06.007

123